1. Field
Example embodiments relate to ferroelectric memory devices and operating methods thereof, and more particularly, to ferroelectric memory devices having reduced interference between cells, increased scalability, and/or a stack structure, and operating methods thereof.
2. Description of the Related Art
With the development of the semiconductor industry, memory devices having a higher density per unit area are generally in demand. Ferroelectric memories are nonvolatile memory devices including a ferroelectric material in a capacitor portion.
Operating principles of ferroelectric memory devices are similar to that of flash memory devices. However, in flash memory devices the concentration of electrons of a floating gate or a charge trap layer causes a shift in a threshold voltage Vth, whereas the threshold voltage in the ferroelectric memory device is shifted according to the polarization direction of the ferroelectric layer.
Nonvolatile memory devices such as electrically erasable programmable read-only memories (EEPROMs) and flash memory devices retain data even if power is cut-off. These types of nonvolatile memories are also capable of programming new data while erasing stored data. Nonvolatile memory devices may be used for semiconductor products such as storage media for mobile devices or portable memory sticks.
With the recent trend in miniaturization of semiconductor products, nonvolatile memory devices included in semiconductor products are becoming more highly integrated. For example, nonvolatile memory apparatuses in which the nonvolatile memory devices are stacked in a three dimensional (3-D) structure may have a relatively high degree of integration in the same plane as compared to nonvolatile memory apparatuses in which the nonvolatile memory devices are stacked in a two-dimensional plane structure.